PPE is an extremely useful thermoplastic resin having excellent heat resistance, mechanical characteristics, electrical characteristics, water resistance, acid resistance, alkali resistance, and self-extinguishing properties and has been broadening its application as engineering plastic material in the field of automobile parts and electrical and electronic parts. However, this resin has a high melt viscosity due to its high glass transition point resulting in poor moldability and poor impact resistance, for example, for use as engineering plastic.
To overcome these disadvantages, PPE has been used as a polymer blend with polyolefin resins or other engineering plastics. However, PPE has been found to have poor compatibility with other polymer resins and plastics, such that resulting polymer blends provide resin compositions which are brittle and which have reduced mechanical strength and impact strength, such that these resin blends are found to be unacceptable for practical use. Additionally, most solubilizers thus for proposed for improving compatibility of PPE with other polymers are graft or block copolymers of PPE and the polymer to be blended. In one feasible method for synthesizing such copolymers, the terminal phenolic hydroxyl group of PPE is made to react with a functional group in the other polymers. However, functional groups capable of reacting with the terminal phenolic hydroxyl group are of limited type, resulting in a narrow range of application of such a technique.
Many terminal-modified PPE resins having improved reactivity have hitherto been proposed. For example, JP-W-62-500456, JP-W-63-500803 and JP-W-63-503391 (the term "JP-W" as used herein means an "unexamined published international patent application") disclose some examples of hydroxyalkylated PPE. However, the processes for producing these modified PPE require multi-stage reactions, some of which are high-temperature melt reactions which are not commercially practical. Even where modification can be achieved under relatively mild reaction conditions, expensive acid chlorides must be used. Further, JP-A-63-128021 (the term "JP-A", as used herein means an "unexamined published Japanese patent application") discloses a process, in which PPE is reacted with ethylene oxide or propylene oxide to introduce a hydroxyalkyl group to the end group thereof. This process still involves several unsolved problems such that a reaction under high pressure is required and, also, control of number of moles of ethylene oxide or propylene oxide added is difficult, resulting in the failure of obtaining products of uniform quality. JP-W-63-503392 teaches a process for introducing an alkoxysilyl group into a PPE skeleton, in which vinyltrimethoxysilane is grafted to PPE in chlorobenzene in the presence of a radical initiator. This process has difficulty in controlling the position at which an alkoxysilyl group is introduced and the amount of an alkoxysilyl group to be introduced.
Although PPE with or without a substituent(s) at the phenylene ring thereof, and especially poly(2,6-dimethyl-1,4-phenylene ether) has excellent heat resistance and mechanical strength and is useful as engineering plastic, it is known to be unsuitable for molding (by injection molding, etc.) due to its high melt viscosity. Additionally, its impact strength and solvent resistance are also not suitable for use as engineering plastic in various applications. As mentioned above, it has been attempted to compensate for such insufficiencies of a resin material, when used alone, by incorporating such a resin material with other resin materials. For example, a PPE composition with improved moldability (which comprises PPE and polystyrene exhibiting compatibility with PPE and satisfactory moldability) has been widely used. However, both PPE and polystyrene have insufficient solvent resistance, as well as does a blend thereof.
Saturated polyesters (e.g., polybutylene terephthalate) have been widely employed as engineering plastics in the field of automobile parts and electric or electronic parts because of their excellent mechanical and electrical properties. However, these resins suffer from the problems of significant molding shrinkage and linear expansion and also exhibit poor thermal stability under high load, and therefore have limited utility. Incorporation of reinforcements, such as glass fibers, has been attempted to overcome these problems, but the resulting molded articles have deteriorated appearance and thus have limited application. Hence, a composition which compensates for unfavorable properties inherent in PPE and a saturated polyester, while retaining the respective favorable properties, would be an excellent resin material with broad applications and high industrial significance. To this effect, a composition obtained by mere melt-mixing of PPE and a saturated polyester was proposed, as described in JP-B-51-21664 (the term "JP-B" as used herein means an "examined published Japanese patent application"), JP-A-49-50050, JP-A-49-75662, and JP-A-59-159847.
Polyamides have been widely employed engineering plastics because of their suitable heat resistance, solvent resistance, and moldability. However, polyamide resins are limited in application due to their inferiority in dimensional stability, hygroscopicity, thermal deformation resistance under high load and impact resistance. Hence, a composition which compensates for unfavorable properties inherent in PPE and a polyamide, while retaining the respective favorable properties, would be an excellent resin material with broad application and high industrial significance. To this effect, a composition obtained by mere melt-mixing of PPE and a polyamide was proposed as disclosed in U.S. Pat. Nos. 3,379,792 and 4,338,421, JP-B-45-997, and JP-B-59-41663. However, such polyamide-PPE blends suffer from significant problems, as described below.
Further, olefin resins are also widely utilized in production of a variety of molded articles because of their moldability, organic solvent resistance, low specific gravity, and cheapness. However, heat resistance of olefin resins is not so high, which has been a hindrance to application as engineering plastic. Hence, a composition which compensates unfavorable properties inherent to PPE and an olefin resin while retaining the respective favorable properties would be an excellent resin material with broadened application and extremely high industrial significance. To this effect, a composition obtained by merely melt-mixing both resins was proposed as disclosed in JP-B-42-706. However, such olefin resin-PPE blends suffer from significant problems, as described below.
However, these conventional mere blends of PPE and other resins, such as saturated polyesters, polyamides and olefin resins, have the following problems. That is, since PPE has poor compatibility with saturated polyesters or polyamides and is substantially incompatible (due to lack of affinity) with olefin resins, the interface of the two-phase structure has insufficient adhesion so that the two phases substantially do not form a uniform and fine dispersion. Such a polymer blend is apt to undergo delamination under shearing stress on molding, such as injection molding, and the resulting molded articles suffer from the problems of deteriorated appearance or defects formed at the interface of the two phases. More specifically, conventional blending of PPE with a saturated polyester fails to provide a composition commercially suitable in mechanical characteristics (e.g., dimensional precision, heat resistance and rigidity) and physical characteristics (e.g., solvent resistance). Additionally, conventional blending of PPE with a polyamide or an olefin resin fails to provide a composition commercially suitable in mechanical strength and impact resistance.
One general approach taken for solving the above-described problem associated with a polymer blend of PPE and a saturated polyester is to chemically bind both polymers by reacting PPE, modified with a functional group capable of reacting with a saturated polyester, and a saturated polyester by melt-kneading at high temperature to obtain a block or graft copolymer having improved affinity between the two polymer components. In this case, it is necessary to initially add to PPE a functional group that is capable of reacting with a hydroxyl end group or a carboxyl end group of a saturated polyester or an ester unit in the main chain of a saturated polyester. In this regard, many functionalized polyphenylene ethers have hitherto been proposed for obtaining increased reactivity. Examples of functionalized PPE proposed to date include a carboxyl- or carboxylic acid anhydride-functionalized PPE (see JP-A-62-257958, JP-A-63-54427, and JP-W-63-500803), an epoxy-functionalized PPE (see JP-A-62-257958 and JP-W-63-503388), and an alkoxysilyl-functionalized PPE (see JP-W-63-503392); and resin compositions of such a functionalized PPE and various saturated polyesters have been proposed. In many cases, however, use of the conventional functionalized PPE proved insufficient for improving compatibility between PPE and saturated polyesters, and the mechanical characteristics of the resulting compositions also were commercially unsuitable, thus requiring further improvements.
Another general approach taken for solving the above-described problems associated with a polymer blend of PPE and a polyamide is to react PPE modified with a functional group and a polyamide by melt-kneading at high temperature to obtain improved affinity between the two polymer components. For such an approach, many functionalized polyphenylene ethers have hitherto been proposed for obtaining increased reactivity. Examples of proposed functionalized PPE include a carboxyl- or carboxylic acid anhydride-functionalized PPE (see JP-W-62- 500456, JP-A-63-10656, and JP-A-63-54427), an epoxy-functionalized PPE (see JP-A-62-257957 and JP-W-63-503388), an amidoor imido-functionalized PPE (see JP-W-63-500803), and an alkoxysilyl-functionalized PPE (see JP-W-63-503392); and resin compositions of such a functionalized PPE and various polyamides have been proposed. In many cases, however, use of the conventional functionalized PPE were still not suitable for improving compatibility between PPE and a polyamide, and the mechanical characteristics of the resulting compositions were commercially unsuitable, such that further improvements were needed.
Another general approach taken for solving the above-described problems associated with a polymer blend of PPE and an olefin resin is to chemically bind both polymers by reacting PPE and an olefin resin, each of which is modified with a functional group capable of reacting with each other by melt-kneading at high temperature to obtain a block or graft copolymer having improved affinity between the two polymer components. Using such an approach, many functionalized polyphenylene ethers have been proposed to date for obtaining increased reactivity. Examples of so far proposed functionalized PPE include a carboxyl- or carboxylic acid anhydride-functionalized PPE (see JP-W-62-500456, JP-A-63-10656, JP-A-63-54427, and JP-A-63-128056), an epoxy-functionalized PPE (see JP-A-62-257957 and JP-W-63-503388), an amido- or imidofunctionalized PPE (see JP-W-63-500803, JP-W-63-503391, and JP-A-61-16963), and an alkoxysilyl-functionalized PPE (see JP-W-63-503392). A number of resin compositions have been suggested that comprise such functionalized PPE's (used as a precursor) and various other resins having a functional group, such as polyamides and saturated polyesters and modified olefin resins. However, such resin compositions have not included a terminal-modified PPE and a modified olefin resin.